Method of making heat transfer panelling



April 8, 1969 J. H. LEMELSON 3,436,816

METHOD OF MAKING HEAT TRANSFER PANELLING Filed Oct. 22, 1965 |o u jFIG.I

2 FIG. 3

2S INVENTOR. JEROME H.LEMELSON FIG. 5

United States Patent 3,436,816 ME'IHUD 0F MAKING HEAT TRANSFER PANELLINGJerome H. Lernelson, 85 Rector St, Metuchen, NJ. 08840Continuation-impart of application Ser. No. 241,904, Dec. 3, 1962. Thisapplication Oct. 22, 1965, Ser. No. 500,731

Int. Cl. Hills: 1/14, 17/00 US. Cl. 29-611 3 @laims This inventionrelates to composite sheet formations and is a continuation-in-part ofmy copending application Ser. No. 241,904 filed Dec. 3, 1962, now PatentNo. 3,276,513, for Composite Screen Assembly having a parent applicationSer. No. 519,014 filed June 28, 1955 for Welding Techniques and nowabandoned. More particularly, this invention concerns new and improvedstructures in metal sheets including sheets having embedded therein oneor more insulated electrical conductors which may be operative to carrycurrent without grounding in the sheet.

It is known in the art to fabricate electrical heating devices byweaving or otherwise securing metal wires or strips to asbestos cloth orother flexible materials which will not melt or deteriorate when theelements are electrically energized. These structures suffer a number ofdisadvantages and shortcomings including, among others, inability toresist penetration and abrasion, inability to support loads and, in manyinstances, the inability to operate at temperatures of more than severalhundred degrees centigrade. Heating panels have been fabricated byapplying an insulating coating to the surface of a metal sheet andbonding on said coating one or more strips of metal capable ofconducting electricity but such structures suffer the shortcoming thatthe conducting strips may be easily penetrated and severed or abraded tocause a break or short-circuit. Furthermore, such conducting panels arenot easily fabricated into many articles by bending the sheet or rollingsame in a mill.

Accordingly, it is a primary object of this invention to provide a newand improved structure in a sheet containing one or more electricalconductors encapsulated within said sheet.

Another object is to provide an improved heating panel madesubstantially completely of metal capable of supporting a substantialload and being fabricated into a structural support member.

Another object is to provide a heating panel made of metal with heatingelements embedded therein and protected by metal on both sides fromabrasion, penetration or shearing actions resulting from contact withobjects while in use.

Another object is to provide an improved heating sheet which may beeasily formed to shape by bending, rolling, stamping or other means soas to permit same to be easily fabricated into equipment components suchas tubing, beams, wall panels, rings, flanges, aircraft skin structuresand the like.

Another object is to provide an improved structure in a metal sheetcontaining a plurality of conducting elements embedded therein withmeans provided for insulating and connecting individual elements toexternal circuits, the sheet being applicable as a wall or otherstructural component of an article of manufacture and serving to hideand support said conducting elements.

Another object is to provide a metal sheet containing conducting wiresembedded therein which serve to reinforce the sheet.

Another object is to provide an improved method for fabricatingcomposite metal sheets.

Another object is to provide an improved electrically conducting panelin which the conductors serve to substantially reinforce the panel. Withthe above and such other objects in view as may hereafter more fullyappear, the invention consists of the novel constructions, combinationsand arrangements or parts as will be more fully described andillustrated in the accompanying drawings, but it is to be understoodthat changes, variations and modifications may be resorted to which fallwithin the scope of the invention as claimed.

In the drawings:

FIG. 1 is an end view in cross section of a panel made in accordancewith the teachings of this invention;

FIG. 2 is an end view in cross section of a fragment of a modified formof the panel of FIG. 1;

FIG. 3 is a side view in partial cross section showing the edge of afragment of a panel of the type illustrated in FIG. 2;

FIG. 4 is an end view in cross section of the components of a panel inmost respects to that illustrated in FIG. 1 prior to the fabricationthereof;

FIG. 5 is an end view in cross section of portions of members utilizedto fabricate a modified form of the invention; and

FIG. 6 is a side view in cross section of a fragment of a panel of thetype defining this invention showing means for electrically connecting alead to a conductor encapsulated within the panel.

The nature of the invention, as to its objects and advantages, the modeof its operation and the manner of its organization may be betterunderstood by referring to the following description taken in connectionwith the accompanying drawing forming a part thereof in which:

FIG. 1 illustrates a structure in a composite metal sheet applicable forthe fabrication of various articles of manufacture which employ as acomponent thereof, a screen, grid or grating made of plural wire-likeelements capable of conducting electricity and/or reinforcing the sheet.The sheet assembly 10 may include, in addition to the components andstructure illustrated, additional components and structural featuresdefining the completed article or product.

One component of the sheet or panel 10 comprises one or more strips,wires or rods 13 provided per se in parallel array or defining a mesh,grid, screen or grating encapsulated or embedded within a metal member12 which may comprise a plate or sheet or portion of a frame or edgesupportv for the wires or grid. The member 12 is preferably, althoughnot necessarily, made of a non-ferrous metal such as aluminum, copper,titanium, brass, zinc, or other non-ferrous metals or alloys capable ofbeing extruded, forged, cast or otherwise provided in the desired sheetor plate shape. The wires 13 may be made of a ferrous metal, electricalresistance material or alloys such as steel or any suitable metalprovided per se or insulated with an outer skin or coating 13' ofelectrical insulating material from the metal of member 12.

The grid or wire array 14 is shown as being made of a plurality ofindividual wires or filaments 13 of metal cylindrical in shape and shownin cross section which may extend in one direction parallel each otheror may be joined by a plurality of longitudinal filaments (not shown)which define a grid or grating.

In FIG. 2 is shown a panel 10' including Wires or strips 20 havingelectrically conductive core portions 21 which are respectively coatedwith insulating layers 22 of nonconductive material such as aluminumoxide, aluminum fluoride, other ceramic or glass, and said coatings aredeformed in situ thereon or on the outer surface strata of the metal asa thin coating or film. Such wires 20 are disposed between two sheets ofmetal, as in FIG. 2, which are compressively engaged and caused to flowcompletely around said elements in a manner to encapsulate them withinthe resulting sheet 12 as described, a new article of manufacture willbe provided which is capable of serving as both a structural and aheating element. By connecting the conducting portions of the filamentsor grid elements with a source of sufiicient electrical energy, they maybe made to serve as resistance heating elements which transfer heat tothe surrounding metal and the resulting sheeting may be used as the skinof a housing aircraft or vehicle or heat transfer device requiring theconductive transfer of heat to one or both surfaces thereof. Theinsulated conducting wires 28 may also be used as conductors per se ofelectricity if the assembly 18' is to be used as the wall of an article,vehicle or panel serving to support said electrical conductors whilecarrying electricity without heating same.

In FIG. 3, the ends 21' of one or more of the encapsulated elements 21are shown extending from the side edge 12e of the metal sheet 12' andmay be bared of insulation 22 beyond sheet 12 for electricallyconnecting same to a source of electrical energy.

The panel assemblies described may be fabricated by various techniquessuch as those illustrated in FIGS. 3 and 4. In FIG. 4 wires 13 are shownpositioned between two members 18 and 19 such as sheets or plates ofmetal such as pressure weldable aluminum. The plates 18 and 19 may beroll bonded or otherwise compressed in a press or rolling mill operativefor compressively engaging the other faces of said plates and causingthe metal of each to flow around the wires or through the openings inthe grid thereof to cause said two members 18 and 19 to becomemolecularly bonded together after completely encapsulating the elements13 therebetween. The faces 18' and 19' of the two sheet or plate members18 and 19 are preferably cleaned and deoxidized just prior to performingthe operation of encapsulating the wires 13 or screen 14 therebetween sothat pressure welding of the assembly will be simplified and suchcleaning may be effected continuously by brushes rotating in line withthe rolling mill.

Following the encapsulation of at least a portion of the wires or screen14 within the metal member 12 as illustrated in FIG. 1, furtheroperations such as bending or rolling may be performed on the assemblyto make articles such as containers, wall panels, tubing or the likethereof.

A screen assembly of the type illustrated in FIG. 1 may be produced bymeans other than that illustrated in FIG. 2. The means to compressivelyengagenthe upper and lower sheets to cause flow of the metal aroundwires 13 or between the spaces or voids in the grid thereof, may bereplaced by a plurality of aligned roller elements such as those of arolling mill through which the two sheets 18 and 19 and wire or gridmembers are passed which rollers are adapted to continuouslycompressively deform the two sheet members in a manner to flow andmolecular bonding of material of each so as to become welded together todefine the unitary structure or edge support illustrated in FIG. 1.

In one form of the invention the composite structure so fabricated willprovide a new type of aluminum or non-ferrous metal sheet which isinternally supported and substantially enhanced in such characteristicsas rigidity, flexural strength, or ability to resist buckling.

In another method of fabricating a panel of the type described, eitheror both the sheets of non-ferrous metal used to encapsulate theconductors therein may be shaped to preposition and retain the insulatedconductors or reinforcing elements in place as shown in FIG. 5. An uppersheet or plate 23 is shown having channels 24 therein aligned with aninsulated conducting strip or strips 27 also shown disposed in channels26 in the lower plate 25. Thus, the facing surfaces 23' and of thesheets 23 and 25 may be brought into abutment with each other andmolecularly bonded or welded together without exerting a shearing actionon the insulation 28 coating or covering conductive core metal 29 of thestrips 27. The shape 41. of the channels in sheets 23 and 24 and strips27 may be such as to cause the strips to be lightly engaged in theresulting passageways when the sheets 23 and 25 are welded. Strips 27may be preshaped, insulated wires positioned within the channels 26 insheet 25 or disposed on the flat upper surafce 25' of sheet 25 on acontinuous basis in alignment with respective channels 24 as the twosheets are rolled to shape, extruded or otherwise continuously fed tothe bite of the roll bonding mill rolls. Strips 27 may also be appliedas a plurality of layers of insulating material and a conducting orresistance heating material disposed therebetween, which layers aresprayed, screened, extruded, rolled or otherwise applied to channels 26or surface 25 just prior to roll bonding or welding sheets 23 and 25together.

While a circuit joining technique involving extending one or more of theencapulated conductors 20 beyond an edge of the sheet, as in FIG. 3, maybe employed to connect electrical energy to the wires within the sheet,in certain applications it may be more desirable to apply the techniqueof FIG. 6 to effect such coupling. FIG. 6 shows sheet 12' having a holeH drilled or otherwise provided therein and extending to element 20. Thedrilling is effected in a manner to bare insulation 22 from 20 so as toexpose a portion of the upper surface of wire or conductor 21. A fitting30 holding a pin or wire conductor 34 is adapted to frictionally fit ahole H and position the end of pin 34 against'the bared portion ofencapsulated conductor 21. Thus 34 may be welded as indicated at W to 21by resistance welding or other means if core 21 is engaged by anothersimilar fitting wire or otherwise grounded.

Fitting 30 is preferably non-conducting material such as a ceramic orplastic resin and has an upper sleeve 31 terminating at a flange 32engaging the surface of 12' and a lower shank 33 shaped to conform totapered hole H to insulate the conductors from grounding on the wall ofsaid hole.

Other means for providing the grid wire elements 20 or grating thereofencapsulated Within a sheet or panel of metal include (a) extruding saidmetal directly onto and causing it to flow through the voids of saidgrid, (b) casting or molding liquid metal around said grid or (c)feeding powdered metal between rollers through which the grid or gratingis also fed and compressively compacting said powdered metal to form aunitary sheet or sent to the particles thereof with the elements of thegrid or grating encapsulated between the surfaces of the fused orsintered sheet. Extrusion encapsulation of the grid or wire elements maybe effected by extruding two sheets of metal such as aluminum, oneadjacent the other and continuously gmiding them towards each otherwhile feeding a web of the screening therebetween and guiding the threemembers between rolls of a roll bonding mill whlie the metal sheets arestill at a high temperature to facilitate molecular bonding andcompressively engaging said sheets to cause them to flow together aroundand between the elements of the grid or screen and to be continuouslymolecularly bonded into a unitary sheet or plate with the gridencapsulated therein. The screen may be fed so that a portion willprotrude from one or more edges of the finished metal plate or sheet, ifused as a resistance heating element or may be totally encapsulated andhidden within the sheet if used solely as a reinforcing means for thesheet. Such techniques may also be employed using ceramics or resins asthe sheet and encapsulating material.

In another form of the invention one or both of the metal sheetsextruded to form the composite sheet may comprise a material other thanmetal such as ceramic, plastic, glass, etc. which may be extruded,roller coated or otherwise applied to a surface of the other sheet andscreening prvided thereon. For example, a thermosetting plastic may beapplied as a spray, flow of powder or roller coated fluid as a layeronto a sheet of metal against which a screen web is fed and retained byroller means. Similarly, particles of glass or other ceramic materialmay be deposited as a layer which covers the screening and fills thevoids therein after which heating applied by any suitable means may beused to fuse the layer into a hard coating. Electrostatic positivelycharging the particles while negatively charging the base metal sheetand/ or screening may be utilized to attract, uniformly distribute andretain the particles in place until heated to form a unitary coating orlayer encapsulating the screening. In still another form of theinvention, a metal grid, grating or screen may be negatively charged andguided between two pairs of drive rolls through free space. Positivelyelectrostatically charged particles of material glass, ceramic, plasticor metal) are directed by conventional spray equipment against thatportion of the negatively charged screening or grating traveling betweenthe drive means at such a flow rate and in a manner to effect thedeposition of particles in a uniform layer or coating around each gridor grating element after which heat is applied by radiant, induction orother means to melt the deposited layer of particles into a unitarycoating around each element whereafter they are allowed to solidify as aprotective coating. Two structures of the finished article may beproduced. In one, the particles are deposited to such a depth that, uponheating and fusing into a coating, spaces or voids between the elementsof the grid or grating will remain so that the grid still retains itsidentity as a grid. [In another method, the particles may beelectrostatically deposited to such a depth on the grating or screeningthat, upon melting or fusing into a coating, the voids between gratingelements will be filled with the particle material. Additionalquantities of particles material may be so electrostatically depositedprior to heat fusion the first time or after heat fusion of the firstmaterial deposited to provide, when melted and fused, not only materialcoating and filling the voids, but also as a further layer extendingbeyond either or both faces of the screening to encapsulate saidscreening therein as illustrated in FIG. 1. The deposited and solidifiedcoating may be subsequently hot or cold worked, if metal or ceramic, toimprove its characteristics.

Noted variations in the panel structures illustrated in FIGS. 1 to 5include fabrication of the main panel body such as 12 and 12' or theformation of FIG. 5 of glass or ceramic materials which are made fromfreshly formed sheets of such materials which are roll bonded orotherwise fused together in a continuous rolling mill or press. If madeof metal, panels 12 and 12 may be bent or fabricated by rolling intotubing and other structural shapes.

I claim:

1. A method of fabricating a metal panel having an electricallyconducting element encapsulated therein comprising:

(a) jacketing an electrically conducting wire in an abrasion-resistanthard electrically insulating coating disposed completely around saidwire,

(b) disposing said wire between two pressure weldable metal members,

(c) compressively engaging said metal members and causing same to deformand flow over and around said wires without removing said insulatingcoating therefrom and pressing the members together to cause molecularbonding of their surfaces and to encapsulate said electrical conductorsin a unitary structure.

2. A method of fabricating an electrically conducting panel comprising:

(a) depositing on a first surface of a metal member a first strip ofelectrically insulating material,

(b) depositing a =flat strip electrical conductor on said first strip ofinsulating material so as to insulate said conductor from said metalmember,

(c) depositing insulating material over said electrical conducting stripand (d) thereafter providing metal against the surface of said firstmetal member and pressure welding said metal thereto in a manner tocompletely encapsulate the metal strip with said non-conducting materialinsulating said metal stripfrom the metal of said first metal member andthat welded thereto.

3. A method of forming a metal panel having a plurality of electricallyconducting elements insulatedly encapsulated within the panel comprisingthe steps of:

(a) exposing the surface of a wire made of electrically conducting metalto an oxidizing atmosphere thereby forming a hard, abrasion-resistantcompound on the surface of said metal defining an electricallyinsulating coating,

(b) disposing said wire against a first surface of a first member ofpressure weldable metal,

(c) bringing a second pressure-weldable metal into surface abutment withthe coated wire,

(d) compressively engaging said first and second members to cause flowof metal of at least one of said members over and around said wire andso as to cause the metal of both said members to flow together,

(d) and continuing the compressive engagement of said metal members tocompletely encapsulate substantially all of the wire without removingthe hard surface coating thereof and to cause the welding of the twometal members together into a unitary structure.

References Cited UNITED STATES PATENTS 2,485,672 10/ 1949 Sparklin219-544 2,497,998 2/1950 Lee 219-544 246,407 8/ 1881 McTighe 29-470.12,701,483 2/ 1955 Foxon et al 29-470.1 2,644,769 7 1953 Robinson 117-172,755,199 7/1956 Rossheim et al. 117-17 3,151,231 9/1964 Steigerwald219-121 3,156,809 11/1964 Stearns 219-121 3,031,739 5/1962 Boggs29-155.63 3,135,040 6/1964 Watson 29-155.63 2,888,614 5/1959 Barnes317-101 3,110,795 11/1963 Bremer 219-544 X 2,169,937 8/1939 Wempe.2,777,300 1/ 1957 Palmer. 2,875,312 2/1959 Norton 29-611 X 3,079,673 3/1963 Loehlein et al. 29-611 3,374,535 3/1968 Tranel 29-611 JOHN F.CAMPBELL, Primary Examiner. J. L. CLINE, Assistant Examiner.

US. Cl. X.R.

1. A METHOD OF FABRICATING A METAL PANEL HAVING AN ELECTRICALLYCONDUCTING ELEMENT ENCAPSULATED THEREIN COMPRISING: (A) JACKETING ANELECTRICALLY CONDUCTING WIRE IN AN ABRASION-RESISTANT HARD ELECTRICALLYINSULATING COATING DISPOSED COMPLETELY AROUND SAID WIRE, (B) DISPOSINGSAID WIRE BETWEEN TWO PRESSURE WELDABLE METAL MEMBERS, (C) COMPRESSIVELYENGAGING SAID METAL MEMBERS AND CAUSING SAME TO DEFORM AND FLOW OVER ANDAROUND SAID WIRES WITHOUT REMOVING SAID INSULATING COATING THEREFROM ANDPRESSING THE MEMBERS TOGETHER TO CAUSE MOLECULAR BONDING OF THEIRSURFACES AND TO ENCAPSULATE SAID ELECTRICAL CONDUCTORS IN A UNITARYSTRUCTURE.